1. Field of the Invention
The present invention relates in general to the elimination of cooling air leakage paths adjacent and through a segmented turbine engine assembly and particularly relates to a combination brush and spline seal assembly for use with an annular segmented turbine engine shroud, nozzle and/or an adjoining annular turbine engine frame.
2. Description of Prior Developments
Turbine engine shrouds and nozzles are mounted within gas turbine engine frames to provide a generally cylindrical or frustoconical surface which defines an annular flowpath through which hot flowing exhaust gasses are directed. Because of the large temperature differentials and the large resultant thermal stresses and strains which are encountered during engine cycling, the annular turbine shrouds and adjoining nozzles are often constructed from a plurality of individual spaced-apart arcuate segments.
Circumferentially-extending gaps or clearances are provided between the confronting axially-extending end faces or side edges of each adjoining shroud and nozzle segment to accommodate circumferentially directed thermal expansion and contraction. Additional clearances are typically provided between the radially extending arcuate end faces located at the axial ends of each shroud and nozzle segment and the adjoining turbine frame members to accommodate axially directed thermal expansion.
The shroud and nozzle segments are typically cooled with pressurized cooling air which bypasses the turbine engine combustor. In order to maintain high turbine engine efficiency, it is important to prevent the cooling air from leaking through clearance gaps located between adjoining shroud and nozzle segments. Cooling air which leaks through these segments enters the exhaust gas flowpath and dilutes the hot flowing gasses thereby adversely affecting engine performance. In order to prevent such leakage, prior segmented shroud and/or nozzle designs relied upon various combinations of axial and radial spline seals, axial spline seals and radial leaf seals and axial spline seals and face seals known as chordal seals.
Unfortunately, no matter how these seals were arranged, some form of cooling air leakage path existed. Because turbine engine performance is improved with better cooling air sealing, a need exists for a sealing assembly which minimizes or eliminates the cooling air leakage associated with conventional seals used between gas turbine nozzle and shroud segments.